Synthesis and properties of novel poly(ether ketone ketone)s containing 1,4‐naphthylene units by electrophilic solution copolycondensation

Abstract

AbstractSemicrystalline poly(aryl ether ketone)s (PAEKs) represent an industrially important class of high‐performance engineering thermoplastics with excellent physicochemical and mechanical properties, and the synthesis of PAEKs with enhanced glass transition temperatures (Tg) and moderate melting temperatures (Tm) is highly desirable. In the work reported, novel poly(ether ketone ketone)s (PEKKs) containing 1,4‐naphthylene units in main chains were synthesized by Friedel–Crafts solution copolycondensation of terephthaloyl chloride with a mixture of diphenyl ether and 1,4‐di(4‐phenoxybenzoyl)naphthalene (1,4‐DPOBN). The polymerization proceeded smoothly in 1,2‐dichloroethane in the presence of anhydrous AlCl3andN‐methylpyrrolidone under mild conditions and afforded polymers having inherent viscosities of 0.66–0.98 dL g−1. The polymers with 5–30 mol% 1,4‐DPOBN are semicrystalline and have obviously enhancedTgover commercial poly(ether ether ketone)s and PEKKs due to the incorporation of rigid and bulky 1,4‐naphthylene moieties into the main chain. The polymers with 20–30 mol% 1,4‐DPOBN not only have highTgof 175–177 °C, but also relatively lowTmof 331–336 °C, having high potential for melt processing. The polymers with 20–30 mol% 1,4‐DPOBN also exhibit excellent thermal stability and good mechanical and solvent‐resistance properties. © 2021 Society of Chemical Industry